Diagnosis of Irritable Bowel Syndrome (IBS)

The diagnosis of IBS is one of exclusion. This means that a firm diagnosis cannot be made until all other causes of your symptoms have been ruled out. This can require a rather extensive evaluation.

Your doctor will begin with questions about your symptoms and medical history, and then perform a physical and rectal exam. Several tests will be done to look for signs of other conditions such as
inflammatory bowel disease
, bowel cancer, infectious disease, and several other intestinal problems.

Most experts currently make the diagnosis of IBS based on the “Rome Criteria”. These criteria are largely based on the symptoms that you report. According to the Rome III Criteria, IBS can be diagnosed when you have two or more of the following symptoms at least three days a month during the preceding three months:

Pain relieved by defecation (having a stool)

Onset of symptoms with a change in stool frequency

Onset of symptoms with a change in stool appearance

Other symptoms such as straining, mucous, or bloating can be used to further support the diagnosis. Tests are often used to “rule out” conditions that may have similar symptoms but with more serious consequences or different treatments.

Tests may include:

Stool Guaiac
—A simple test for traces of blood in the stool. It can be done at the time of your physical exam.

Stool Cultures
—This involves examining a stool sample in the laboratory to look for infectious agents.

X-ray of the Bowel
(
Barium Enema
)—Barium is a dye that makes the inside of your intestines visible on an x-ray. Many conditions can be identified with this technique. You will be given instructions about how to completely empty your bowel before the test.

Sigmoidoscopy
—A long, thin, lighted tube with fiberoptic vision is inserted through the rectum to examine the rectum and the lower part of your colon. This can be done in your doctor's office.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.